1998 Chevy Tahoe Dies Out While Driving

My 1998 Chevrolet Tahoe kills while driving. It has happened only on long trips and the service engine light doe not come on. It starts back up and runs fine, but the engine has killed more than once, just not back to back. One time after the engine killed, I drove to gas station and it died while idling. I have been told that the electronic control module (ecm) could be overheating on long trips but I just want a second opinion. I went to a service station and the guy said if it didn't relay any signal to the computer via the engine light coming on, he could not diagnose it. Any help is greatly appreciated.